For fireflies, getting the girl requires team work

Imagine you drive into a motel in Gatlinburg TN, and see behind an open room door 2 guys setting up cameras pointing at the beds while two young women peek from the parking lot. Well, if it was in the mid ’90’s it might have been Drs Moiseff and Copeland setting up the equipment before venturing into Elkmont in the Smoky Mountains to study the local fireflies. (And one of the two women would have been me.)

Andy Moiseff and Jon Copeland started studying the population of fireflies in the Smoky Mountains National Park after learning from Lynn Faust, who had grown up in the area, that they produced their flashes in a synchronous pattern.

Image courtesy of Andy Moiseff

In the species they are studying (Photinus carolinus) the males produce a series or bursts of rhythmic flashes that are followed by a ‘quiet period’. But what is particularly interesting about this species is that nearby males do this in synchrony with each other. If you stand in the dark forest, what you see is groups of lightning bugs beating their lights together in the dark night pumping light into the forest in one of nature’s most beautiful displays.

Females flash in a slightly different manner and, as far as I know, they don’t do it synchronously either with other females nor with the males. One interesting thing in Elkmont is that there are several species of fireflies, and you can pretty much tell them apart by their flashing patterns. But as useful as this is for us biologists (since it avoids having to go through extensive testing for species determination), the question still remained of whether the flashing patterns played a biological role.

And this is what Moiseff and Copeland addressed in their latest study published in Science. They put females in a room where LEDs controlled by a computer simulated individual male fireflies. The LEDs were made to flash with different degrees of synchronisation and they looked at the responses of the females. They found that while the females responded to synchronous flashes of the LEDs, they really didn’t seem to respond when the flashes were not synchronous. Even more, they responded better to many LEDs but not much to a single one. What this means, is that if you are a male of Photinus carolinus, you better play nice with your mates if you want to get the girl.

What *I* want to know is how this behaviour is wired in the brain. At first hand, this seems like a rather complex behaviour, but in essence all that it seems to require is a series of if/then computations, which should not be too hard to build (at least not from an ‘electronic circuit’ point of view). But Bjoern Brembs reminded me of a basic concept in neuroscience: brains are evolved circuits, not engineered circuits. So, Andy and Jon, how *do* they do it?